1. Technical Field
The present invention relates to digital maps that can be used for route guidance by a navigation system and, in particular, to the management and display of signposts in digital maps.
2. Related Art
The use of navigation systems in vehicles is becoming increasingly prevalent. Typically, on-board navigation computer systems analyze the combined data provided by GPS (global positioning system), motion sensors such as ABS (anti-lock braking system) wheel sensors, and a digital map to determine the actual position and velocity of a vehicle with increasing preciseness.
Navigation systems typically use electronic digital maps to represent cartographic features, such as streets, buildings and rivers, and store the data that relates to the cartographic features on a compact disk or a digital video disc. After performing a map matching algorithm, the actual position of the user may be indicated in the digital map. By acoustic and/or visual information, the user may be guided to a predetermined destination.
Some navigation systems are able to display detailed digital maps indicating routes to destinations, the types of maneuvers to be taken at various locations such as intersections as well as different kinds of points of interest (e.g., gas stations, restaurants and signposts). As the vehicle changes position, either the vehicle position mark on the displayed image changes or the digital map may be scrolled while the vehicle position mark is fixed at a predetermined position.